Re: [Xen-devel] [PATCH] x86/shim: fix ballooning up the guest

[Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>]

On 17/03/2020 10:24, Jan Beulich wrote:
> On 16.03.2020 22:47, Igor Druzhinin wrote:
>> args.preempted as meaningless here and doesn't show if the hypercall
>> was preempted before. Use start_extent instead which is correct.
> 
> ... as long as the hypercall was invoked in a "normal" way.
> 
>> Signed-off-by: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
>> ---
>> This fixes ballooning for 64-bit PV guests inside shim. 32-bit PV guests
>> require a little bit more work due to compat layer being involved.
>> ---
>>  xen/common/memory.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/xen/common/memory.c b/xen/common/memory.c
>> index 444c081..5fdd2a2 100644
>> --- a/xen/common/memory.c
>> +++ b/xen/common/memory.c
>> @@ -1191,7 +1191,7 @@ long do_memory_op(unsigned long cmd, 
>> XEN_GUEST_HANDLE_PARAM(void) arg)
>>          }
>>  
>>  #ifdef CONFIG_X86
>> -        if ( pv_shim && op != XENMEM_decrease_reservation && 
>> !args.preempted )
>> +        if ( pv_shim && op != XENMEM_decrease_reservation && !start_extent )
>>              /* Avoid calling pv_shim_online_memory when preempted. */
>>              pv_shim_online_memory(args.nr_extents, args.extent_order);
> 
> The code change can have my R-b, but I'd like the comment to also
> be changed then - it shouldn't talk about preemption in the way
> it does. Perhaps "... when this is a continuation"? I'd be okay
> making this change while committing.

Sure, if you like.

> As an aside, it would probably have been a good idea to also Cc
> Roger as the original author of this code.

I didn't check "git blame" and he wasn't on a maintainers list.

Igor

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